dg2d.font source code

1 /*
2   Copyright Chris Jones 2020.
3   Distributed under the Boost Software License, Version 1.0.
4   See accompanying file Licence.txt or copy at...
5   https://www.boost.org/LICENSE_1_0.txt
6 */
7 
8 module dg2d.font;
9 
10 import dg2d.misc;
11 import dg2d.truetype;
12 import dg2d.path;
13 
14 /*
15   This is very much "just get it working so I can print something on screen",
16 */
17 
18 Font loadFont(string filename)
19 {
20     import dg2d.misc;
21 
22     ubyte[] tmp = loadFileMalloc(filename);
23     if (tmp.ptr == null) return null;
24 
25     ttFontInfo finfo;
26     if (ttLoadFont(finfo, tmp) == ttFail) return null;
27     Font font = new Font();
28     font.m_data = tmp;
29     font.m_fontinfo = finfo;
30     return font;
31 }
32 
33 // cast away const on font data for now till I can fix truetype stuff to work with const
34 
35 Font loadFont(const(ubyte)[] rawfont)
36 {
37     import dg2d.misc;
38 
39     ttFontInfo finfo;
40     if (ttLoadFont(finfo, cast(ubyte[]) rawfont) == ttFail) return null;
41     Font font = new Font();
42     font.m_data = cast(ubyte[]) rawfont;
43     font.m_fontinfo = finfo;
44     return font;
45 }
46 
47 class Font
48 {
49     this()
50     {
51     }
52 
53     ~this()
54     {
55         dg2dFree(m_data.ptr);
56     }
57 
58     // setSize, just going on this for now...
59     // https://docs.microsoft.com/en-us/typography/opentype/spec/ttch01
60 
61     void setSize(float size)
62     {
63         m_size = clip(size, 1, 200); // what are plausible limits for size?
64         m_scale = size * 72.0 / (72.0 * 2048.0); 
65     }
66 
67     float addChar(ref Path path, float x, float y, uint charCode)
68     {
69         int gid = ttCharToGlyph(m_fontinfo, charCode);
70         if (gid == 0) return 0.0f;
71 
72         if (m_prevGlyph > 0)
73         {
74             x += ttGetKerning(m_fontinfo, m_prevGlyph, gid)*m_scale;
75         }
76         ttAddGlyphToPath(m_fontinfo, gid, path, x, y, m_scale, -m_scale);
77         return ttGetAdvanceWidth(m_fontinfo, gid)*m_scale;
78     }
79 
80     float lineHeight()
81     {
82         return (ttGetFontAscent(m_fontinfo) - ttGetFontDescent(m_fontinfo)
83            + ttGetFontLineGap(m_fontinfo)) * m_scale;
84     }
85 
86     float height()
87     {
88         return (ttGetFontAscent(m_fontinfo) + ttGetFontDescent(m_fontinfo)) * m_scale;
89     }
90 
91     // horizontal advance for a given glyph taking into account kerning. It needs the
92     // next character to properly evaluate, pass 0 if there is none
93 
94     float glyphAdvance(uint charCode, uint nextCode)
95     {
96         int g0 = ttCharToGlyph(m_fontinfo, charCode);
97         int g1 = ttCharToGlyph(m_fontinfo, nextCode);
98         return (ttGetAdvanceWidth(m_fontinfo, g0) +
99             ttGetKerning(m_fontinfo, g0, g1)) * m_scale;
100     }
101 
102     // getTextSpacing, calculates the spacing for each character in txt,
103     // note: advance array must have same length as txt
104 
105     void getTextSpacing(const char[] txt, ref float[] advance)
106     {
107         assert(txt.length == advance.length);
108 
109         int lb1 = cast(int)txt.length-1;
110         for(int i = 0; i < lb1; i++)
111         {
112             int g0 = ttCharToGlyph(m_fontinfo, txt[i]);
113             int g1 = ttCharToGlyph(m_fontinfo, txt[i+1]);
114             advance[i] = (ttGetAdvanceWidth(m_fontinfo, g0) +
115                 ttGetKerning(m_fontinfo, g0, g1)) * m_scale;
116         }
117         advance[$-1] = ttGetAdvanceWidth(m_fontinfo, ttCharToGlyph(m_fontinfo, txt[$-1]));
118     }
119 
120     // get width of txt
121 
122     float getStrWidth(const char[]  txt)
123     {
124         if (txt.length == 0) return 0;
125 
126         float w = 0;
127         for(int i = 0; i < txt.length-1; i++)
128         {
129             int g0 = ttCharToGlyph(m_fontinfo, txt[i]);
130             int g1 = ttCharToGlyph(m_fontinfo, txt[i+1]);
131             w += (ttGetAdvanceWidth(m_fontinfo, g0) +
132                 ttGetKerning(m_fontinfo, g0, g1)) * m_scale;
133         }
134         return w + ttGetAdvanceWidth(m_fontinfo, ttCharToGlyph(m_fontinfo, txt[$-1])) * m_scale;
135     }
136 
137 private:
138     ubyte[]     m_data;
139     ttFontInfo  m_fontinfo;
140     float       m_size;
141     float       m_scale;
142     uint        m_prevGlyph = -1;
143     bool        m_doKerning = true;
144 }
145